1. Field of the Invention
The invention relates to novel radiation-sensitive 1-sulfonyloxy-2-pyridones, chromophorically substituted in the 6-position, to a process for preparing them and to their use, preferably in a radiation-sensitive mixture.
2. Description of Related Art
The use of 1-sulfonyloxy-2-pyridones as photooxidants in radiation-sensitive mixtures which contain a leuco dye has been disclosed by U.S. Pat. No. 4,425,424. In such mixtures, the photooxidant effects during irradiation, for example, an oxidation, causes the leuco dye to undergo an intensive color change and causes a visual contrast between exposed and unexposed areas. Such color changes are desired in industry, for example in the production of printing forms, in order to enable the copying result to be assessed after exposure, and before development.
1-Benzenesulfonyloxy- and 1-(toluene-4-sulfonyloxy)-2-pyridone and processes for the preparation thereof are known (E. C. Taylor et al., J. Org. Chem., 35, 1672, 1970). The radiation sensitivity of these compounds was, however, not recognized.
Sulfonic acid esters as acid generators in radiationsensitive mixtures are known. Examples of these are the sulfonates of hydroxymethylbenzoin derivatives (see DE-A 1,919,678) or 2-nitrobenzyl sulfonates (see EP-A 0,330,386) and pyrogallol sulfonates (see T. Ueno et al., Chemical Amplification Positive Resist Systems Using Novel Sulfonates as Acid Generators, in "Polymers for Microelectronics - Science and Technology", edited by Y. Tabata et al., Kodansha-Weinheim-New York, 1989, pages 66-67). Such radiation-sensitive sulfonic acid esters are, due to their absorption properties, particularly suitable for irradiation with high-energy UV2 radiation, that is, 220 to 280 nm. However, their sensitivity to the UV3 and UV4 radiation (350 to 450 nm) currently used in industry is inadequate for use in practice.
Compounds which have sensitivities suitable for practice in this region are known from EP-A 0,137,452. These are, for example, compounds which contain trichloromethyl groups and, on exposure, from free chlorine radicals and hydrochloric acids, which confer the desired properties as photoinitiators or photo-acid generators on these compounds. The photolytically generated hydrohalic acids, however, have a strongly corrosive action and, for this reason, cannot be used in many technical fields.